Underreamer



ocr. 5, 1937. H C, SMWH f 2,094,855

UNDERREAMER Filed J`u1y112, 1955 2 sheets-sheet 2 Patented oct. 5, 1937UNITED STATES PATENT OFFICE 11 Claims.

This invention relates to underreamers, and particularly to that formofv underreamer which may be used with rotary well apparatus.

The invention contemplates an underreamer snv constructed and arrangedthat cutter elements thereof may be brought into or out of workensagement at the will of the operator.

An object of the invention is the provision of a rotary underreamerutilizing rotary cutters, said cutters being positively actuated intowork engagement at any given location within a well hole and under knownWorking conditions to the well operator.

As is well known, underreamers are utilized for the purpose of enlarginga well hole, Cable tool underreamers are well known in the art, but thepresent invention may comprise a bit secured in advance of theunderreamer. As the bit drills a hole of a given size, the underreamerwill follow and ream the hole to a larger size or diameter and beneaththe lower end of the casing within the well hole. In fact, it ispossible with the present tool to follow the underreamer with casing,where ordinary care is used that the underreamer does not contactthecasing shoe.

The cutters of the present underreamer are toothed and are so arrangedwith relation to the longitudinal axis of the underreamer body that thesaid cutters may be collapsed within the said body or eccentricallydisposed relative to the periphery of the body and its axis to bring thecutters into formation engagement.

It is an object of the present invention to provide an underreamerwherein the cutter elements are so associated and interrelated thatlikelihood of damage thereto is in a large measure obviated. Y

It is a further object, in this connection, to provide an underreamer offew working parts, thus lessening the likelihood of damage ornonfunctioning of the various elements of the underreamer.

A further object is the provision of an underreamer of the rotary typewhich provides for a proper cleaning of the cutters during anunderreaming Operationfto the end that the cutters will not becomeclogged or otherwise renderedinefficient. Thus, by properly cleaning thecutters, it is evident that the cutters will actually ream the formationat all times. Hence, a more rapid Vunderreaming than is usual may beobtained.

Another object is the provisionY in an underreamer of novel meanswhereby the cutter elements of said underreamer may be readilydisassembled from the body or reassembled Within the minimum of timethrough the simple expediency of the removal of a single keeper member.

Other objects of the invention, include simplicity of structure,Vinexpensiveness in cost of manufacture, and general efficiency of thedevice.

With the above mentioned and other objects in View, the inventionconsists in the novel and useful provision, formation, construction,association and interrelation of parts, members and features, all asshown in a certain embodiment in the accompanying drawings, describedgenerally, and more specifically pointed out in the claims.

In the drawings:

Figure 1 is an elevation of the improved underreamer shown partly incross section, with the underreamer positioned within a well hole priorto underreaming the formation below a well casing, shown in section,

Figure 2 is a fragmentary vertical sectional view of the underreamerconstruction and on an enlarged scale from the showing of Figure 1,

Figures 3, 4 and 5 are transverse sectional views taken oncorrespondingly numbered sectional lines of Figure 2, and

Figure 6 is a transverse sectional View, certain elements of theinvention being in a changed relationship from that of Figurev.

Referring now with particularity to the drawings, the underreamer isdesignated as an entirety by the numeral I, and the said underreamer inFigure 1 is positioned within a well hole 2. The lowermost end of casing3 is positioned above cutter elements designated generally as 4. Thepresent underreamer I carries a iish tail bit 5 at one end thereof. Theopposite end of the underreamer may be secured in any approved manner tothe drill string l. Referring to Figure 2, the underreamer I includes anelongated body 'I provided With a central bore, designated generally as8, and which may vary as to diameter. For instance, the bores 9 and I0may be of greater diameter than the bore I I. This` bore is, of course,for circulation purposes. One end of the body is. provided with atapered threaded box I2 concentric with the bore 8, while the oppositeend of the body may be provided with a threaded pin I3. The diameter ofthe pin is less than the diameter of the body, this constructionaffording an annular shoulder I4. The opposite end of the body in thezone of the box may be externally tapered, as shown at I5, The body isformed to best carry the cutter elements 4. These cutter elements may bearranged in groups and in the present instance, three groups of cutterelements are provided, as designated generally and shown in Figure e, asgroups I6, i1 and i8. As all of the groups are identical in constructionbut a single group will be described, like numerals applying to theother groups.

The group I6 is shown in Figure 2, and comprises four toothed cutterrollers i9, 28, 2l, 22, and 23.

For the purpose of holding the cutter rollers in assemblage as a group,I have provided a shaft 24. This shaft is provided with eccentric endportions 25 and 26, and the main body 21 of the shaft, interposedbetween the eccentric end portions, is provided with plane faces 23 and29. The

cutter roller i9 is adapted to t around the shaft at the plane faceportion 28 thereof. The bore of the roller I3 is provided with aiiattened portion for engagement with the plane face 28, to the end thatany rotation of said roller produces rotation of the shaft 24,considered as an entirety. The cutter rollers 26, 2| and 22 are free torotate about the main body 2'! of the shaft. The roller 23 ,has itscentral bore provided with a flattened portion adapted to closely engagethe plane face 29 of the shaft. As will be seen by viewing Figures 5 and6, this cutter roller is provided with segmental teeth 30. The rollersi9 and 23 may be considered as actuating members for the shaft. In orderto hold the shaft with its cutter rollers mounted thereon in position tothe body of the underreamer, I have provided in the underreamer anelongated channel inwardly eX- tending from the periphery thereof, asindicated at 3l. This elongated channel is concave in cross section, asbest shown in Figures 4 to 6, in that zone occupied by the cutterrollers. Portions at each end of the concaved channels are so formed inthe body as to best accommodate bearing blocks 32 and 33 for holding theshaft 24 and the assembled cutter rollers thereon to the body. In thisrespect, it will be seen that the upper bearing block 32 has its upperend face 34 inclined or at an angle to the side faces thereof, and thatthe body 1 of the underreamer is likewise provided with an inclined face35 for matching engagement with the face 34. A transverse section of theblock 32 is illustrated in Figure 3, and the said block is provided witha journal portion 36 adapted to receive the shaft portion 25. A bore 31extends inwardly from the inclined face 34 and the rear face 38 of theblock is formed in part with a half circle bore 39. The bearing block 33is provided with an inclined or tapered end face 40 adapted to bereceived upon an inwardly tapered face 4I of the body 1, and this saidblock is formed with a bore 42 to receive the shaft portion 26.

The body 'i in the zone of the half-bore 39 of the block iscorrespondingly half-bored at 43 so as to provide a substantiallycomplete circular bore, and a transverse bore 44 communicates with thetwo cooperating half bores and with the bore portion 9 of the bore 3.The shoulderV i4 is provided with a threaded bore 45 adapted to receivea centering and locking pin 46, threaded in part as shown at 41. It willbe seen that the assemblage of a cutter set within the body is simple ofaccomplishment, in that the shaft carrying the bearing blocks with thecutter rollers and actuating rollers interposed therebetween may bereadily positioned within a channel of the body of the underreamer,through the simple expediency of placing the blocks in position and thencausing the centering and locking pin 46 to be received Within the bore3l or" the block 32, as illustrated in Figure 2.

A stud `48 is positioned adjacent the periphery of the actuator roller23, this stud being secured within the channel 3l of the underreamerbody. The actuator roller 23 is stopped in its movement by a toothedportion engaging one of the two sides of the said stud, as bestillustrated in Figures 5 and 6.

The operation, uses and advantages of the invention just described areas follows:

We may assume that, in the present embodiment, three complete sets ofcutter rollers, as illustrated at I6, il and i8, are provided, with thesaid underreamer secured to a drilling string 6. The sh tail bit 5 issecured to the underreamer and in advance thereof, to the end that theiish tail bitV mayywhen the drill string is rotated,

cut the formation While the underreamer follows and enlarges the cuthole. During well drilling, it is customary to circulate a fluid throughthe drill string, to the end that the sh tail bit does not freeze andthis circulation through the drill string passes in turn through thebore 8 of the underreamer and outwardly through openings in the sh tailbit, as illustrated at 49. A portion of the circulation fluid passesthrough the openings 43 and within the concaved channels surrounding thecutter rollers of the underreamer. In Figure 1, it will be observed thatthe casing 3 is located at a given position within the well hole andwhen it is desired to lower the casing to a greater depth Within thewell hole, it is customary to enlarge the well hole through the mediumof an underreamer. This underreamer must pass through the casing andquite obviously the cutters should not contact the inner surface of thecasing and cause damage to both the casing and the underreamer cutters.Hence, after the underreamer has passed from beneath the lower end ofthe casing and drilling commences, the cutter members of the underreamermay be brought into formation engagement by rotating the drill string.This rotation, which would be clockwise or to the right, viewing Figurel, will cause the slightly projecting teeth of the actuating roller 23to engage the formation and rotate the roller from the position shown inFigure 6 to that shown in Figure 5. This rotation will rotate the shaft24 to project the cutter roller teeth beyond the periphery of theunderreamer body,

as shown in Figure 4. As rotation of the underreamer continues, it isevident that the cutter rollers are maintained in their outward cuttingposition by a tooth of the actuator roller 23 engaging'the stop 48, seeFigure 5. Hence, as long as rotation continues and the drillingoperation proceeds, the cutters will rotate about the shaft and rearnthe hole. The cutter teeth are at all times maintained in substantiallya clean condition and free from cuttings by the flow of fluid aroundsaid cutters, a feature of importance. Vfhen it is desired to releasethe cutter rollers from formation engagement, the tool may be rotated tothe left, and the uppermost actuator roller will engage the formation aswill likewise the lowermost actuator roller 23 and rotate the shaft orshafts from the position of Figure 5 back to the position shown inFigure 6, to move the cutter rollers substantially fully within theconcaved channels or .grooves to the end that the teeth do not projectsubstantially beyond the periphery of the body of the underreamer.

When it is desired to replace worn cutter rollers, or actuators, it isonly necessary to remove the pin 45 and the bearing blocks, togetherwith the assembled rollerson the shaft between the bearing blocks, fromthe body of the underreamer. Removing one or the other of the bearing.vblocks will allow the cutters and cutter actuatorsltobe removed from theshaft. AVeryv little time is necessary for this operation.

It is usual practice to use a casing shoe at the lower end of thecasing, and 'if the underreamer cutters are not collapsed inwardly ofthe body upon counterrotation, due in part to the factV reamerk cuttersvary as to diameter fro-m thek lowermost actuator cutter 23 to theuppermost actuator cutter I9, with the result that each cutter performsits full degree of work. No one cutter performs work to the exclusion ofa contiguous cutter. l Y Y.

A feature of importance in the present invention resides in the methodof positioning the bearing blocks withinthe body. It is to be noted thatthe relation of the bearing blocks to the keeper pin is such that stressforces the bearing blocks inwardly ofthe body, with the result that ifthe pin should become dislodged there is still little likelihood of thebearing blocks or the cutters becoming disengaged from the body, whichwould result in a fishing job.

Another feature resides in the arrangement of the water passage throughthe body l with relation to the port openings 44. fluid passed throughthe bore 9 will not have as high a velocity as a fiuid passed throughbore Il due to the difference in diameter. There will also be a tendencytoward back pressure of the fluid with resultant forcing of the fluidthrough the port openings 44 and into the half bores 39 and 43 at a highvelocity, which Velocity, in actual practice, has been found sufficientto thoroughly clean the cutter teeth and keep olf debris during acutting operation. This construction is equivalent to nozzle action.

I claim:

1. An underreamer including a body in longitudinal alignment with thedrilling string by which it is to be rotated, a shaft carried by thebody and rotatable relative thereto, a cutter roller carried on saidshaft, and an actuator roller` secured to said shaft, said shaft havingits axis of rotation eccentric to the axis of rotation of the cutterroller.

tion of which shaft is eccentric to the axis of saidV cutter roller, therelationship being such that movement of the actuator rotates the shaftto move the said cutter roller into the said channel or outwardlytherefrom.

Obviously, the K 3. An. underreamer' including a body formed, with alongitudinal peripheral channel, a shaft, bearing .blocks for ends ofsaid shaft, said bearing blocksV andv shaft adapted for placementwithin,

said channel, a cutter roller free to rotate on said shaft, an actuatorroller secured to the shaft, and means adaptedY to limit the rotation ofsaid actuator roller in two directions, movement of said actuator rollerin one direction projecting said cutter roller beyond the periphery ofthe underreamer body and movement of the cutter roller in a seconddirection moving said cutter roller Within the channel.

4. An underreamer comprising a body adapt? edtoV be rotated, a shafthaving end portions thereof rotatably secured in said body, and anintermediate portion the axis of which is eccentric to the axis of saidend portions, a cutter roller rotatably carried on the intermediateportion of the shaft, and a further cutter roller secured toene of thesaid end portions.

5, An underreamer comprising a body in longitudinal alignment with thedrill string by which it is to be rotated, said body provided with alongitudinally extending channel opening finblocks adapted to bereceived within said channel,

a cutter roller, and an actuator roller on said shaft, said actuatorroller secured to said shaft andthe-cutter roller free to rotate on saidshaft, the axis of rotation of said shaft relative to the bearing blocksbeing eccentric to the axis of rotation of said cutter roller.

6. An underreamer comprising a body in 1ongitudinal alignment with thedrill string by which it is to be rotated, said body provided with alongitudinally .extending channel opening inwardly from the peripherythereof, a shaft, bearing blocks for ends of said shaft, said bearingblocks adapted to be received within said channel, a cutter roller, anactuator roller on said shaft, said actuator roller secured to saidshaft and the cutter roller free to rotate on said shaft, the axis ofrotation of said shaft relative to the bearing blocks being eccentric tothe axis of rotation of said cutter roller, and said cutter roller.

7. An underreamer including a body provided with a central bore, saidbody formed with a longitudinal channel `eccentric to the axis oi said lbore, a shaft, and end bearing blocks for said shaft, said bearingblocks both provided with inclined end portions and said body havingcomplementary inclined portions in the zone of said channel, and meansfor securing one of said beari ing blocks to the body when both saidbearing blocks are within said channel.

8. An underreamer including a body, a pair of spaced v apart bearingblocks, a shaft received within said bearing blocks, and a cutter rolleron said shaft and between said bearing blocks, the end faces of saidbearing blocks being angularly related other than 90 to the axis of saidshaft, said body provided with a channel, the end walls bounding whichare angled complementary to the ends of the bearing blocks, and meansfor securing one of said bearing blocks to said body whereby the bearingblocks, shaft, and cutter roller are maintained secured to said body.

9. An underreamer comprising a body arranged in longitudinal alignmentwith the drilling string by which it is to be rotated, said body formedwith an axial iiuid passageway communicating with the drilling string, ashaft, a cutter roller free to rotate on said shaft, said shaft havingend portions, the axis of which is eccentric to that portion of theshaft around which said cutter roller rotates, bearing vblocks for eacnend of said shaft, said body provided with an eccentric chan- 5 nelformed to receive the bearing blocks, shaft and said roller, means forlocking said bearing blocks to said body when received within saidchannel, an actuator roller keyed to said shaft at an eccentric endportion thereof, and means between said body and said actuator rollerfor limiting the rotation thereof and whereby when the underreamer isrotated in one direction, and said actuator roller held, the said shaftwill move said cutter roller outwardly of the said channel to l5 engageformation, and counterrotation of said underreamer body, said actuatorroller being held,'will retract the said cutter roller within saidchannel. v

10. An underreamer comprising a body arranged in longitudinal alignmentwith the drilling string by which it isto be rotated, said body formedwith an axial fluid passageway communieating with the drilling string, ashaft, cutter rollers free to rotate on said shaft, said shaft havingend portions, the axis of which is eccentric to that portion of theshaft around which said cutter rollers rotate, bearing blocks for eachend of said shaft, said body provided with an eccentric channel formedto receive the bearing blocks, shaft and said rollers, means for lockingsaid bearing blocks to said body when received within said y channel, anactuator roller keyed to said shaft at an eccentric end portion thereof,means between said body and said actuator roller for limiting therotation thereof and whereby when the underreamer is rotated in onedirection, and said actuator roller held, the said shaft will move saidcutter rollers outwardly of the said channel to engage formation, andcounterrotation of said underreamer body, said actuator roller beingheld, will retract the said cutter rollers within said channel, andmeans for by-passing any fluid passed through the drill string and thesaid underreamer body into the zone of said cutter rollers to maintainsaid cutter rollers free of cuttings.

ll. An underreamer including a body, a pair of spaced apart bearingblocks, a shaft received between said bearing blocks, and a cutterroller on said shaft; the end face of one of said bearing blocks beingat an angle other than to thel axis of said shaft, said body providedwith a channel, one end wall bounding said channel being at an anglecomplementary to the angled face of a bearing block, said body providedwith a threaded bore opening externally the body, and a threaded pin forreception within said thread- .ed bore for engagement with the other ofsaid bearing blocks, whereby when said complementary body end wall andbearing block face coengage and the pin engages the other bearing block,said bearing blocks, shaft and cutters are maintained secured to saidbody.

HERMAN C. SMITH.

